Barbara is packing a wedding gift that is contained within a rectangular box 20 by 18 by 4 in. How much wrapping paper will she require?

a. 512 in²

b. 1,440 in²

c. 1,024 in²

d. 92 in²

c. The surface area of the box is the add of the areas of all six sides. Two sides are 20 by 18 in or (20)(18) = 360 in². Two sides are 18 by 4 in or (18)(4) = 72 in². The last two sides are 20 by 4 in or (20)(4) = 80 in². Adding up all six sides: 360 in² + 360 in² + 77 in² + 77 in² + 80 in² + 80 in² = 1,024 in², is the total area. If you select a, you did not double all sides. If you select b, you determine the volume of the box.